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Stereotypy and asymmetry in mice
1Laboratory of Psychobiology, Harvard Medical School, Boston, MA.
Summary
Cocaine administration significantly increased running in mice, inducing unidirectional movement. This suggests that drug-induced stereotypy, not inherent asymmetry, drives this behavior.
Area of Science:
- Neuroscience
- Animal Behavior
- Pharmacology
Background:
- Locomotion patterns in rodents are crucial for understanding motor control.
- Cocaine is known to affect motor activity and induce stereotyped behaviors.
Purpose of the Study:
- To investigate the effect of cocaine on the directionality of circular locomotion in mice.
- To differentiate between stereotypy and asymmetry as causes of unidirectional running.
Main Methods:
- Mice were trained to run in a circular runway.
- The number and direction of circuits completed were recorded.
- Mice received a cocaine administration (100 µmol/kg) and their locomotion was re-evaluated.
Main Results:
- Control mice exhibited balanced running in both directions.
- Cocaine administration resulted in a 3.5-fold increase in circuits, with most mice running unidirectionally.
- Some mice showed directional preference shifts after repeated cocaine doses.
Conclusions:
- Cocaine induces a strong bias towards unidirectional running in mice.
- The observed unidirectional running is primarily driven by drug-induced stereotypy.
- Stereotypy, rather than pre-existing motor asymmetry, is the main factor influencing cocaine-induced unidirectional locomotion.